If there is any symbolism implied in the Candidate’s starting off ‘with the left foot,’ it has now been forgotten, and it can only be supposed that the request to the candidate is nothing more than an attempt to ensure that he and his guide proceed in step. But this is a matter in which we might easily be wrong, for the custom might have been derived from folklore. James Grant, in his Mysteries of all Nations, states that “it is thought lucky to step out with the left foot first.”

There is always the possibility that the custom of starting off with the left foot was introduced in the military lodges of the eighteenth century. Bearing in mind that a right-handed man, in particular a soldier carrying arms at his left side, naturally tends to start off with the left foot, as otherwise he might lose balance, it is easy to see that what originally was a matter of drill might quite naturally have become a ceremonial detail in purely military lodges, which, from their migratory habits and their strongly ‘Antient’ sympathies, are known to have exerted marked influence on masonic ritual and custom from their institution in Ireland in 1732 and England in 1750 right on through the 1700s…

Perhaps it is worth while recalling, however, the extremely ancient superstition (based probably on an earliest religious idea) that a person entering another man’s house on his left foot took ill luck in with him, and the apparent contradiction of this when the masonic Candidate, who is undoubtedly crossing the threshold of a mystic building, starts his perambulation in the lodge on his left foot… It may be conjectured as to whether the intention of instructing the Candidate to start with the left foot was that he should step over and not on the threshold of the symbolic lodge.

Brother Dan-O, that was a fantastic find with that paper, thanks!!
I think Lark may be on to it. I know that most modern militaries march starting with their left foot. Even though, many times, they call it out “by the right!!” The “right” merely indicates where the cadence caller is located though.
This may be a masonic mystery never to be solved. But, there was some fantastic reading about it!